1. Field of the Invention
The present invention relates to a pressure control apparatus of an airbag, and more particularly, to a pressure control apparatus of an airbag, which can perform as a dual stage inflator even in case of using a single stage inflator by having a pressure control apparatus for selectively communicating the interior of an airbag cushion and the exterior of an airbag housing without using the dual stage inflator.
2. Description of the Related Art
FIG. 1 is a schematic view showing an airbag system of a vehicle according to the conventional art. FIG. 2 is a schematic view showing a conventional dual stage inflator.
A conventional airbag is adapted such that an airbag cushion may be deployed to a passenger side in the event that a car crash occurs at a specified speed, and the passenger protection standards are designed such that an average adult male may receive optimal protection in a specified posture. This condition is set forth as normal seating condition. Thus, if a passenger is in an unsafe posture, or has a physique smaller than the average physique, or is a child hereinafter, abbreviated as “abnormal seating condition” or “OOP (out of position) condition”), they may be seriously injured due to a high pressure upon deployment of the airbag cushion of the conventional airbag device.
The airbag system in accordance with the conventional art includes, as shown in FIG. 1, an airbag housing 2, an impact detection sensor (not shown) for detecting an impact in the event of a collision of a vehicle, a dual stage inflator 1 for instantaneously inflating gas, and an airbag cushion 3 disposed within the airbag housing 2 and deployed upon collision.
Here, the dual stage inflator 1 refers to, as shown in FIG. 2, an inflator that is configured to expand the airbag cushion 3 along with the blow out of a powder gas caused by the explosive force of an explosive charge and has two or more igniters 1a and 1b for igniting the explosive charge.
The operational procedure of the thus-constructed airbag system in accordance with the conventional art will be described below.
First, as shown in FIGS. 1 and 2, when the impact detection sensor (not shown) detects an impact of a predetermined magnitude or more, a control unit selectively ignites any one or both of the two igniters 1a and 1b according to whether a high or low pressure deployment of the airbag cushion 3 is required.
At this time, the control unit is programmed to make instruction signal to the dual stage inflator 1, based on a pre-set state condition of collision, in conjunction with a vehicle speed sensor (not shown) and a seat position detection sensor (not shown) for detecting the distance between a seat (not shown) on which a passenger is seated and an airbag module.
The state condition of collision may be a high pressure deployment condition in which a high pressure deployment of the airbag cushion 3 is required and a low pressure deployment in which a low pressure deployment is required. The high pressure deployment condition corresponds to the normal seating condition and the low pressure deployment condition corresponds to the normal seating condition or OOP condition set forth above.
In other words, the control unit ignites both of the igniters 1a and 1b if a high pressure deployment condition of the airbag cushion 3 is required, and ignites one of the igniters 1a and 1b if a low pressure deployment condition is required, thereby effectively protecting the passenger in a normal seating condition or OOP condition.
Next, if the igniters 1a and/or 1b are ignited by control of the control unit, the airbag cushion 3 is expanded with a high pressure or a low pressure by the blow out of a powder gas caused by the explosion of an explosive charge, and thus deployed toward the passenger.
However, the above-described airbag system in accordance with the conventional art has the problem since it is necessary to provide a costly dual stage inflator for selectively performing high pressure deployment or low pressure deployment of the airbag cushion in order to effectively protect a passenger in both normal seating condition and abnormal seating condition.
Such a dual stage inflator is expensive compared to a single stage inflator generating a single pressure, and this causes an increase in the production cost of the product.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known to a person skilled in the art.